Electromagnet.



C. L. I H. L. KRUM.

RNET.

ELECTROMA APPLICATION FILED JUNE I, I908- RENEWED AUG.

Patentedi Mm. 21", 191?,

magmas UNITED STATES PATENT OFFICE.

CHABLESL. KBUM AND HOWARD L. KRUM, OF CHICAGO, ILLINOIS, ASSIGNOBS TO MOBKBUM COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

ELEC'I'BOMAGNET.

Specification of Letters Patent.

Patented Mar. 2'1, 1917.

Application fled June 1, 1908, Serial No. 486,169. Renewed August 18, 1916. Serial No. 115,679.

To all whom it may concern.

Be it known that we, CHARLES L. KRUM and HOWARD L. KRUM, citizens of the United States, and residents of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Electromagnets, of which the following is a specification.

The invention relates to electro-magnets and to electro-magnetic relays and seeks to provide an improved construction which may be cheaply manufactured in large quantities and which will be sensitive and positive in operation, and which will not readily get out of order. The improved electromagnet is particularly designed for use in connection with relay switch contacts mounted upon the armature of the electro-magnet and upon the frame thereof. The invention consists in the features of improvement hereinafter set forth, illustrated in the accompanying drawings and more particularly pointed out in the appended claims.

In the drawings Figure 1 is a side elevation of the improved electro-magnet or relay. Fig. 2 is a longitudinal section thereof. Fig. 8 is a plan view, and Fig. 4 is a perspective vow of difi'erent parts of the magnet.

The improved electro-magnet has a straight, hollow core 1 that is formed of suitable magnetic metal, such as soft iron or annealed steel, and is preferably split lengthwise to cut down the eddy currents. Such magnet cores may be conveniently and cheaply formed from metal tubing cut to proper lengths. End pieces 2 and 3 of indurated fiber or like insulating material are provided with openings slightly smaller than the core and are forced onto the ends of the latter. The core is then provided between the end pieces 2 and 3 with an insulating wrapping 1 of shellacked paper. The coil 5 of the magnet is wound upon the core between the end pieces 2 and 3 and its ends are connected to two terminal posts 6 and 7 that are threaded into suitable openings in the outer edge of the upper end piece 2.

A flat pole piece 8 and a flat, supporting or frame bar 9 extend across and in contact with the upper and lower ends respectively of the core 1. A connecting screw bolt 10 having a head at its upper end extends through. an opening in the pole piece 8 and through the hollow core 1, and its lower end is threaded through a suitable opening in the supporting bar 9 so that these parts are securely connected together, with the pole piece 8 and frame bar 9 projecting laterally from. the upper and lower ends of the core and at right angles thereto. 'The pole piece 8 and bar 9 are formed of suitable magnetic material, such as soft iron or annealed steel.

A flat armature bar 11 is pivotally connected to the supporting frame bar 9. The latter is preferably provided with an upturned extension 12 which is parallel to the core and to the upper end of which the armature bar 11 is pivoted. The latter extends across the projecting edge of the pole piece 8 and is arranged to be attracted thereby to complete the magnetic circuit through the pole piece, core 1, and bar 9. The extension 12 is provided at its upper edge with a central, interlocking lug or tongue 13 that fits snugly within a recess between a pair of lugs or tongues 1 1 upon the lower edge of the armature bar, and a pivot pin 15 extends laterally throu hthe interlocking lugs or tongues 13 an 14. By this arrangement the armature bar is pivotally sustained, and at the same time a good path is maintained for the passage of the lines of force through the magnetic circuit. To hold the armature bar 11 and pole piece 8 in roper relation, the pole piece, the bar 9, and the core 1, are provided with interlocking tongues and grooves. In the form shown, the pole piece 8 is provided on its under face, and the bar 9 is provided on its upper face, with an interlocking groove 16. These grooves interlock with parallel tongues 17 formed upon the opposite ends of the core 1. Suitable tools can be provided for turning out core 1, pole piece 8, bar 9, and armature 11 inexpensively in large quantities, and these parts may then be quickly and easily assembled in proper position and securely. held in proper relation by the connecting screw bolt '10 and pivot pin 15. The ends of the pivot pin "15 are preferably upset to hold the armature bar securely in position upon the end of the extension 12. The interlocking tongues and grooves 16 and 17 between the ends of the core 1 and the pole piece 8 and bar 9 prevent any twisting of the pole piece 8 and bar 9 upon the ends of the core so that the armature bar 11 and the face of the pole piece 8 are always held in parallel relation, and the pole piece, which projects at right angles toward the armature bar, will act, quickly and positively, when an energizing current is passed through the coil 5 to attract the armature bar. The armature bar is normally held away from the pole piece 8 by a leaf spring 18 which is secured atits lower end to the inner face of the extension-12 by screws 19, the upper end of which presses outwardly against the inner side of the armature bar 11. The bar 9 is provided with one or more openings so that the magnet may be secured in upright position to a'suitable base board 20 by screws 21.

One or more contact springs 22 are secured by screws to the armature bar 11 and project upwardly therefrom. There are two of these spring contact fingers in the form shown, and they are insulated from the armature bar and from the fastening screws 23 by a flat piece 24 and flanged sleeves 25 of fiber or other suitable insulating material.

The fastening screws 23 extend through the insulatingsleeves 25 and are threaded in suitable openings in the armature bar 11.

The sleeves 25 fit within openings formed in the contact springs and in the flat insulating strip 24 so that the contact springs are securely held against the face of the insulating strip 24 by the flanges on the sleeves25. The contacts with which the spring fingers 22 cooperate are carried upon a suitable contact support or upright 26 which is provided with an oflset foot piece 27 at its lower end which abuts against the outer face of the upright extension 12 and is secured thereto by screws 28. The back contacts 29 are mounted upon the upper endot the upright 26 and the latter is provided atone side of its upper end with an extension 26 bent to lL-shape to support the front contacts 30. The back contacts are insulated from the support or upright 26 by a strip 31 and flanged sleeves 32 of fiber or other suitable insulating material. The contacts 29 extend through the flanged sleeves 32 and are provided with hexagon heads 33 at their inner endswhich abut against the flanged ends of the insulating sleeves 32. The latter fit within openings formed in the upper end of the upright 26 and in the insulating strip 31. Nuts 34 threaded on the outer ends of the contact pieces 29 hold the latter in place and also serve to secure the clips 35 thereto.

These clips are provided with openings in naaonaa ends with nuts 40 which bear against the flanged inner ends of the sleeves 39. The

latter extend through openings in the lug or extension 26* and in the insulatin strip 38 which is placed against the outer ace of the lug. A lock-nut 41 on the contact screw 30 holds the latter in adjusted position. A clip 42 is provided. with an opening at its lower end, through which the metal sleeve. 36 extends, and the flange on the outer end of this sleeve serves to hold the clip in place. The latter projects upwardly so that the conductors leading to the front contacts 30 may be conveniently attached thereto.

A block 43 of insulating material is secured to the upright 26 just below the insulating strip 31 by screws 44. This block is wider than the strip'31 and carries two upwardly.projecting clips 45 which are secured thereto by rivets 46. Conductors 47 secured to the lower ends of the fastening strips 45, extend through flanged insulating sleeves 48 set within openings in the lower end of the upright 26, and connect with the lower ends of the contact spring fingers 22.

The spring 18 normally holds the armature bar "11 away from the pole piece 8 with the contact springs 22 in engagement with the contacts 29. When an energizing cur rent is passed through the coil5, the armature will be drawn toward the pole piece 8 and the contact spring fingers 22 will be brought into firm engagement with the contact screws 30. To prevent the armature from freezing to the pole piece the latter is preferably provided with a pair of small spacing studs 49 of brass or like non-magnetic material. If desired a stop screw 50 may be threaded through an opening in. the

upright 26 so as to engage one of the screws 23 and hold the armature innormal position. This stop screw is not necessary unless the back contacts 29 are omitted.

The construction is simple and compact. All of the arts may be economically manufactured, elther by stamping thesame out from sheet metal with suitable tools, or by an automatic screw machine. The parts may be easily and quickly assembled in proper relation. The armature bar is arranged to complete the magnetic circuit through the pole piece and frame bar secured to the opposite ends of the core. The switch contacts of the relay are at the upper end of the device so that they may be readily inspected and adjusted and so that the connections of the conductors thereto may be easily made. The switch contacts are effectively insulated and the relay may be employed to control circuits of 100 volts or more.

It is obvious that numerous changes may be made in the details set forth without dcparture from the essentials of the invention as defined in the claims.

Having described our invention, what we claim as new and desire to Secure. byLet ters Patent, is

1. An electro-magnet comprising a straight core provided with an energizing coil, a flat pole ieoe and a fiat supporting bar separate rom and extending across the ends of said core at right angles thereto, said parts having interlocking tongues and grooves on opposite sides of the axis of said core to hold said pole piece and supporting bar against relative angular movement, fastening means extending through said pole piece and supporting bar and axially through said core, a flat armature bar pivotally connected to said supporting bar and extending across the projecting edge of said pole piece and switch contacts operated by said armature, substantially as described.

2. The combination of a straight,hol1ow core provided with an energizing coil, a projecting pole piece and a supporting bar extending across the opposite ends of said core, said parts having interlocking tongues and grooves, a connecting screw bolt extending through said parts, and an armature pivoted to said su port and arranged to be attracted by sai pole piece, and switch contacts operated by said armature, substantially as described. i

3. The combination of a straight, hollow core provided with an energizing coil, a flat pole piece and a flat supporting bar extending across the ends of saidcore at rightangles thereto, said parts having interlocking tongues and grooves, a connecting screw bolt extending through said parts, a flat armature bar pivotally connected to said supporting bar and extending across the projecting edge of said pole piece,-and switch contacts operated by said armature, substantially as described.

4. The combination of a straight, hollow core provided with an energizing coil, afiat armature bar and a fiat supporting bar of magnetic material extending across the ends of said core at right angles theretr:i

said parts having interlocking tongues an grooves, a connecting screw bolt extending through said parts, said supportihg bar having an upturned extension parallel to said core, a flat armature bar ivoted to said extension and extending in line therewith across the projecting edge of said pole piece, and switch contacts operated by said armature.

- 5. The combination of a straight core provided with an energizing coil, a flat pole piece and a flat supporting bar of magnetic material secured tothe ends of said core and projecting laterally therefrom, said supporting bar having an extension parallel to said core, a flat armature bar pivoted to said extension and extending in line therewith across the projecting edge of said pole piece, a contact support secured to said extension and extendiiig beyond the end of said armature, a stop screwin said contact support for engaging said armature, springs secured to said extension and engaging said arma ture to hold the same against said' stop screw, insulated spring contact fingers secured to said armature and cooperating insulating contact screws mounted upon the end of said contact support, substantially as described.

6. The combination of an electro-magnet comprising a core provided with an energizing coil, a pole piece and a supporting frame secured to opposite ends of said core, an armature pivoted to said supporting frame and extending acrom the end of said pole piece, a spring and an adjustable stop screw for holding said armature in normal position away from said pole piece; a spring contact finger mounted on said armature, and one or more fixed contacts mounted on said supporting frame and arranged to be engaged by said contact finger, substantially as described. I

7. The combination with a straight, electro-magnet coreprovided with an energizing coil, of a pole piece and a supportlng extending beyond the end of said armature and a series of insulated contacts mounted on the end of said support and arranged to be engaged by said spring fingers, substantially as described.

8. The combination with a straight, electro-magnet core provided with an energizino coil, of a pole piece and a bar of magnetic material secured to opposite ends of said bar at right angles thereto, said bar having an extension parallel to said core,

a spring held armature bar pivoted to said extension and extending across the pro-l jecting edge of said pole piece, a lurality of insulated spring fingers secure to said armature, a contact supporting bar fixed to said extension and extending parallel with and beyond the end of said armature, and a series of insulated contacts mounted on the end thereof and arranged to be engaged by said spring fingers, substantially as described.

9. The combination with a straight electro-magnet core provided with an energizing coil, of a flat pole pieceand a flat bar of magnetic material extending across and interlocked with the opposite ends of said pole piece, said bar having an upturned extension, a. fiat armature bar pivoted to said extension and extending upwardly across the projecting edge of said pole piece, one or more upwardly extending spring fingers secured to said armature loar, an uprightsecured at. its lower end to said extension and projecting upwardly albove the end of said armature bar, and one or more contacts carried on the upper end of said upright and arranged to be engaged by said spring fingers, substantiallyas dethe opposite ends of said coil, and inter locked therewith by tongues and grooves, a connecting screw extending through said parts, said barhaving an upturned extension, a flat armature bar pivoted to said extension and extending in linetherewith across the projecting edge of said pole piece, a flat, upright bar secured at its lower end to said extension, a plurality of insulated spring fingers secured to said armature bar and projecting upwardly therefrom, and insulated contacts mounted on said upright bar on o posite sides of said spring fingers, substantlally as described.

CHARLES L. KRUM. HOWARD L. KRUM. Witnesses:

Hanna L. Crier-P, KATHARINE German. 

